The present invention relates to forklift machines, and more particularly to systems for supporting or stabilizing forklift machines.
Forklift machines or "forklifts" used to lift, transport and deposit loads are generally well known. A typical forklift machine generally comprises a chassis or frame, two pair of wheels mounted to axles attached to the frame and a lifting mechanism including a pair of movable arms or "forks". In use, an operator located in an operator cab maneuvers the vehicle to approach a load and engages the forks of the lift mechanism with the load, such as a pallet or crate of manufactured goods, a load of lumber or steel, etc. The lift mechanism raises the load and the forklift transports the load to a desired destination, where the load is then lowered and deposited.
One problem with forklift vehicles, particularly when lifting and/or transporting heavy loads on uneven terrain, is that the weight of the load may give rise to a moment about either the front pair of wheels and/or the right or left side pairs of wheels (e.g., the right side front and rear wheels) of the forklift. Such a moment, if not properly counteracted by moments arising from other forces, for example the weight of the forklift frame, may cause the forklift to "topple" over and lose the load. Therefore, support or stabilizing systems have been developed to counteract load-generated moments to prevent toppling of the forklift.
To prevent such toppling, systems have been developed whereby at least one and generally two stabilizing arms having an end contactable with the base surface at a location forward of the front pair of wheels. Generally, these systems are formed by a pair of arms, each arm having one end connected to the forklift machine and the other end being contactable with the base surface, and a pair of hydraulic cylinders each moving a separate connected arm. With such systems, the tendency of the load to tilt the vehicle forwardly about the front wheels causes the ends of the arms to press against the base surface, generating normal forces that, acting through the stabilizing arms, exert a moment directed oppositely the load moment. The moment exerted through the stabilizer arms (in combination with the moment generated by the weight of the forklift) is sufficient to prevent the forklift from toppling forwardly.
However, known stabilizing systems, such as those discusse above, have certain problems. With systems having stabilizer arms mounted to one of the vehicle axles, the axle must be reinforced to support stabilizer mechanism and the loads transmitted to the axle through the stabilizer arms. Further, as the stabilizer mechanisms are located beneath the forklift frame, the stabilizer system is both difficult to access for service purposes and have a limited range of vertical travel. Other systems having the arms connected to frame, the arms must generally be mounted proximal to the lateral sides of the frame so that the arms do not interfere with operator's field of vision when located in an upward storage position. Being mounted near the sides of the frame, the arms must be pivoted a relatively greater distance to cause a corresponding vertical displacement of the frame, thus requiring greater cylinder extension distances compared with axle-mounted cylinders.
It would therefore be desirable to have a system for supporting or stabilizing a forklift vehicle that overcomes the above-described drawbacks or limitations of the previously known support systems.